The invention concerns a double chain stitch sewing machine with a machine upper section and a machine lower section which sections between themselves define a sewing product plane parallel to which plane the machine sections are movable in synchronism, with the machine upper section having a needle rod for holding a needle and movable by a drive perpendicularly to the sewing product plane and the machine lower section having a hook cooperating with the needle for forming stitches, which hook is movable back and forth in a plane parallel to the movement direction of the needle rod.
Double chain stitch sewing machines of the aforementioned kind in which a machine upper section and a machine lower section are rigidly connected with one another have been known for decades. Moreover, machines of the above mentioned kind have also been known in which a machine upper section and a machine lower section are mechanically separated from one another or at least are not directly connected with one another, but by way of synchronously controlled drives have been capable of being driven in common along the sewing product plane. Such machines have been used for example for the sewing of quilts or mattress covers. Also common are previously known double chain stitch sewing machines in which the sewing direction is predetermined by the construction of the sewing machine. For example, in the sewing of mattress covers the sewing product web is pulled from a supply roll, and therefore in the case of a change in the direction of the sewing the machine upper section and the machine lower section must be rotated in common into the new sewing direction, since the sewing product itself cannot be rotated. In connection with this it is known to rotatably support the machine upper section and the machine lower section about the needle axis. This rotation of the machine upper section and machine lower section requires an additional drive and a corresponding control. Moreover, at each change of direction the sewing drive must be braked and subsequently again accelerated.